Historically, meat products have been butchered and packaged in individual supermarkets or other retail outlets. It has long been recognized that this arrangement is extremely inefficient and expensive. Instead, it would be preferable to butcher and package the meat at a central efficient facility that benefits from economies of scale, and then to ship the meat to individual supermarkets or other retail outlets. Moreover, because of problems with waste disposal, butchering at a central location is preferable.
In the past, this desirable goal has not been achievable because most consumers prefer to buy meat which is red in color as a result of exposure to oxygen. However, the meat maintains its red color for only one to two days. Thereafter, it turns a purple color which is undesirable to most consumers.
Therefore, if the meat were butchered and packaged in one location and then shipped to another location for eventual sale, by the time the package reached the retail outlet the meat would have undergone the transformation to the purple color and would be effectively unsalable.
To overcome these problems, there have been a number of efforts to maintain the food product in a first atmosphere during shipping and a second atmosphere when the meat product is ready for retail sale. It is not believed that any of these techniques have yet achieved significant commercial acceptance. Therefore, it is highly desirable to provide a package that would permit remote meat preparation, and subsequent sale several days later.
One problem is that while the need for such a package is great, consumers may not be willing to invest much money in elaborate packages. Thus, it would be highly desirable to have a package that is convertible between two very different packaging conditions, and yet is very economical. Moreover, it is also advantageous for the package to look similar to packages to which consumers are currently accustomed.
One attempted solution to these problems is to use a dual layer cover over a plastic package containing the meat product. The upper cover is gas impermeable and may be removed to expose a lower cover that is air permeable. Thus, the package may be shipped with the upper cover intact so that a inert gaseous atmosphere may be maintained within the package during shipping. Then the upper cover may be removed at the supermarket leaving the lower cover. Since the lower cover is oxygen permeable, it allows the meat to bloom in the presence of oxygen.
Conventionally, such dual layer packages have been implemented by adhesively securing the upper layer to the lower layer and thereafter heat sealing or otherwise securing both layers to the package itself. For example, when the upper layer is removed the adhesive may be retained on the lower layer, interfering with the ability of the lower layer to pass oxygen. Also, when removing the top layer it may be difficult to avoid tearing or otherwise removing the lower layer. Moreover, it is difficult to produce such a package with controlled delamination of the two layers.
While various elaborate techniques have been conceived for avoiding the interference between the layers, these approaches generally add cost and complexity to the packaging. Moreover, the removal of the upper layer (which is sealed to the lower layer) without removing the lower layer is problematic. Although attempts have been made to overcome these problems, no commercially viable solution has been achieved.